[PATCH 2/2] iotests: add throttle test

[Vladimir Sementsov-Ogievskiy]

Add simple test for throttle filter driver.

Without previous
"block/throttle-groups: use QEMU_CLOCK_REALTIME for qtest too"
commit the test hangs forever, because previously used VIRTUAL clock
just doesn't tick for iotests.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@openvz.org>
---
 tests/qemu-iotests/tests/throttle     | 50 +++++++++++++++++++++++++++
 tests/qemu-iotests/tests/throttle.out |  0
 2 files changed, 50 insertions(+)
 create mode 100755 tests/qemu-iotests/tests/throttle
 create mode 100644 tests/qemu-iotests/tests/throttle.out

diff --git a/tests/qemu-iotests/tests/throttle 
b/tests/qemu-iotests/tests/throttle
new file mode 100755
index 0000000000..63b802cee7
--- /dev/null
+++ b/tests/qemu-iotests/tests/throttle
@@ -0,0 +1,50 @@
+#!/usr/bin/env python3
+# group: auto
+#
+# Simple test for throttle filter driver.
+#
+# Copyright (c) 2022 Virtuozzo International GmbH
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+import iotests
+
+with iotests.VM() as vm:
+    vm.launch()
+
+    result = vm.qmp('object-add', {
+        'qom-type': 'throttle-group',
+        'id': 'group0',
+        'limits': {'bps-write': 512 * 1024}
+    })
+    assert result == {'return': {}}
+
+    result = vm.qmp('blockdev-add', {
+        'node-name': 'throt',
+        'driver': 'throttle',
+        'throttle-group': 'group0',
+        'file': {
+            'driver': 'null-co',
+            'size': 1024 * 1024
+        }
+    })
+    assert result == {'return': {}}
+
+    result = vm.hmp_qemu_io('throt', 'write 0 512K')
+    assert result == {'return': ''}
+
+    # We need second write to trigger throttling
+    result = vm.hmp_qemu_io('throt', 'write 512K 512K')
+    assert result == {'return': ''}
diff --git a/tests/qemu-iotests/tests/throttle.out 
b/tests/qemu-iotests/tests/throttle.out
new file mode 100644
index 0000000000..e69de29bb2
-- 
2.35.1